ME8451 Manufacturing Technology – II Question Bank Unit 1 – Theory of Metal Cutting

1. List the various metal removal processes? a. Non cutting process or chip less process. b. Cutting process or Chip process

2. How chip formation occurs in metal cutting? The material of the work piece is stressed beyond its yield point under compressive force .This cause the material to deform plastically and shear off.

3. What is wear? During machining the tool is subjected to three important factors such as forces, temperature and sliding action due to relative motion between tool and work piece. Due to these factors tool will undergo wear.

4. Mention the cutting fluids? Two basic types are (i) Water based cutting fluids (ii) Straight or heat oil based cutting fluids

5. Draw the nomenclature of cutting tool geometry or cutting tool signature.

6. Compare orthogonal and oblique cutting

7. Define tool life. Tool life is defined as the time elapsed between two consecutive tool re- sharpening. During this period the tool serves effectively and efficiently.

8. What are the objectives and functions of cutting fluids? (i) It is used to cool the cutting tool and work piece (ii) It improves surface finish (iii) It protects finished surface from corrosion (iv) It washes away chips from tool 9. Briefly explain the effect of rake angle during cutting? Effect of back rack angle: For softer material greater angle should be given for harder material smaller angle is enough Effect of Side rack angle: Curling of chip depends on this angle.

10. What are the factors responsible for builtup edge in cutting ? (i) Low cutting speed (ii) Small rake angle (iii) Coarse feed (iv) Strong adhesion between chip and tool face.

11. List out the essential characteristics of a cutting fluid. (i) It should have good lubricating properties (ii) High heat absorbing capacity (iii) High flash point (iv) It should be odorless

12. Name the various cutting tool materials. (i) Carbon tool steel (ii) High speed steel (iii) Cemented carbides (iv) Ceramics (v) Diamonds

13. Give two examples of orthogonal cutting. (i) (ii) Facing (iii) Thread cutting (iv) Parting off

14. What are the four important characteristics of materials used for cutting tools? (i) Hot hardness (ii) Wear resistance (iii) High thermal conductivity (iv) Easy to grind and sharpen (v) Resistance to thermal shock

15. What is the function of chip breakers? The chip breakers are used to break the chips into small pieces for removal, safety and to prevent both the machine and work damage

16. Name the factors that contribute to poor surface finish in cutting. (i) Cutting speed (ii) Feed (iii) Depth of cut

17. Define the term machinability and machinability rating. Machinability:- It can be defined as ability of being machined the components and more reasonably as ease of machining. Machinability rating:- Relative machining response of the work materials compared to that of a standard metal was tried to be evaluated quantitatively only based on tool life (VB* = 0.33 mm) by an index

18. Write a short note on Heat zones in cutting.  Primary shear zone (1) where the major part of the energy is converted into heat • Secondary deformation zone (2) at the chip – tool interface where further heat is generated due to rubbing and / or shear • At the worn out flanks (3) due to rubbing between the tool and the finished surfaces

19. Write a short note on any two modern tool materials. (a) Coated carbides (b) Cermets (c) High Performance Ceramics (HPC) (d) Cubic Boron Nitride (cBN) (e) Diamond Coated Carbides:-The properties and performance of carbide tools could be substantially improved • Refining microstructure • Manufacturing by casting – expensive and uncommon • Surface coating – made remarkable contribution. Thin but hard coating of single or multilayers of more stable and heat and wear resistive materials like TiC, TiCN, TiOCN, TiN, Al2O3 etc on the tough carbide inserts (substrate) by processes like chemical Vapour Deposition (CVD), Physical Vapour Deposition (PVD) etc at controlled pressure and temperature enhanced MRR and overall machining economy Cermets:- These sintered hard inserts are made by combining ‘cer’ from ceramics like TiC, TiN, TiCN and ‘met’ from metal (binder) like Ni, Ni-Co, Fe etc. Since around 1980, the modern cermets providing much better performance are being made by TiCN which is consistently more wear resistant, less porous and easier to make.

20. What are the main requirements of cutting tool materials? i) High mechanical strength; compressive, tensile, and TRA ii) Fracture toughness – high or at least adequate iii) High hardness for abrasion resistance iv) High hot hardness to resist plastic deformation and reduce wear rate at elevated temperature v) Chemical stability or inertness against work material, atmospheric gases and cutting fluids vi) Resistance to adhesion and diffusion vii) Thermal conductivity – low at the surface to resist incoming of heat and high at the core to quickly dissipate the heat entered viii) High heat resistance and stiffness ix) Manufacturability, availability and low cost.

21. List the physical function of a in machining. The physical functions of a machine tool machining are (i) Firmly holding the blank and the tool (ii) Transmit motions to the tool and the work piece (iii) Provide power to the tool-work pair for the machining action (iv) Control of the machining parameters.

22. Classify the types of cutting fluids. Oils - mineral, animal, vegetable, compounded, and synthetic oils, Emulsions - a mixture of oil and water and additives Semisynthetics - chemical emulsions containing little mineral oil Synthetics - chemicals with additives

23. What do you understand by the term “Tool Designation or Tool Signature”? Consider the example

ORA System –6º, –6º, 10º, 15º, 15º, 45º, 1.2 (mm) Inclination Angle (λ) = –6º, Orthogonal Rake Angle (γ) = –6º, Orthogonal Clearance Angle (α) = 10º, Auxiliary Orthogonal Clearance Angle (αo’) = 15º, Auxiliary Cutting Edge Angle (Φ1) = 15º, Principal Cutting Edge Angle (Φ) = 45º, Nose Radius (r) = 1.2 mm.

24. What are the factors that affect the tool life? Work piece material, Tool Geometry, Use of cutting fluid, Process parameter

ME8451 Manufacturing Technology – II Question Bank Unit 2 – Turning Machines

1. What are the various thread cutting methods? (1) Reversing the machine. (2) Marking the parts (3) Using a chasing dial or thread indicator (4) Using thread chaser

2. What is Swiss type automat? In this type, the work piece is feed against the tool. The head stock carrying the moves back and forth for providing the feed movement in the longitudinal direction.

3. Explain the following parts of lathe? (a) Lathe bed (b) Carriage Lathe bed: It is the base of the machine. It carries headstock on its left end and tailstock on its right end. Carriage: It is the moving part that slides over the guide ways between headstock and tailstock.

4. What is an apron? It is an integral part of several , levers and clutches which are mounted with saddle for moving the carriage along with lead while thread cutting.

5. List any four methods by which taper turning is done in a center lathe. (i) Form tool method (ii) Tailstock set over method (iii) Compound rest method (iv) Taper turning attachment method

6. Distinguish between Capstan lathe and .

S CAPSTAN LATHE TURRET LATHE No 1 Turret head is mounted on a Turret head is directly mounted ram which slides over the on saddle .But it slides on the saddle. bed

2 Turret movement is limited Turret moves on the entire length of the bed without any restriction.

7. Mention four different types of chucks used in a . (i) Three jaw (or) self centering chuck (ii) Four jaw chuck or independent chuck (iii) Magnetic chuck

8. What is the purpose of a mandrel? How many types of mandrels is there in common use? Mandrels are used for holding hollow work pieces (1) Plain mandrel (2) Collar mandrel (3) Cone mandrel (4) Step mandrel (5) Gang mandrel

9. What are the advantages of using a collect chuck? (i) Job setting will be easy and quicker (ii) Heavy cut can be taken

10. Why is it essential that the cutting point of the tool should be level with the center while machining taper on a work piece? It is done to avoid eccentric taper.

11. What is the difference between a ram type turret lathe and saddle type turret lathe?

S RAM TYPE TURRET LATHE SADDLE TYPE TURRET LATHE No 1 Turret head can be moved Turret head cannot be moved manually manually.

2 The maximum size of 60mm It can accommodate only from diameter work can be 125 to 200mm. accommodated.

12. Calculate the power required for cutting a steel rod of 50mm in diameter at 200rpm. Assume cutting force of 160 kg. Power Required = FC X V = FC x DN = (160 x 9.81) x 1000 X 50 X 200 X 1000 X 60 = 821.8 kW

13. What are the advantages of automatic ? (i) Mass production of identical parts. (ii) High accuracy is maintained (iii) Time of production is minimized. (iv) The bar stock is fed automatically.

14. What are the functions of feed rod and lead screw? Feed Rod: It is used to guide the carriage in a straight then moves along the bed. Lead screw: It is used to move the carriage while thread cutting operation is carried out. It also ensures the proper speed of work relative to the tool for thread cutting operation.

15. Why was power chucks developed? Power chucks are primarily developed for the application as work holding divides for automatic machines, and CNC machines

16. Give the specification of a lathe The size of the lathe is specified as follows i) The length between the centres ii) The length of bed iii) The height of the centres iv) The maximum diameter v) The swing diameter of the bed vi) The swing diameter over carriage

17. What is meant by “swing of the lathe”? Swing over bed refers to the maximum diameter of work piece the lathe can handle. Swing over cross slide means the maximum diameter that will clear the cross slide.

18. What do you mean by copy turning? Copy turning is carried out on special lathes that control the cutting tool in some manner to produce identical items. The copy lathe uses a template to guide the cutter. They are capable of creating good quality components for little expense in patterns and setting up. Sanding is usually carried out by hand.

19. List out the various types of lathe. (i) Speed lathe (ii) Engine lathe (iii) Bench lathe (iv) Tool room lathe (v) Semi-Automatic lathe (vi) Automatic lathe (vii) Special purpose lathe (viii) Copying lathe

20. How are automatic lathes are classified?

21. What are the various mechanisms are used for a automatic feeding in lathes? (i) Tumbler mechanism (ii) Quick change gear box mechanism (iii) Tumbler gear mechanism (iv) Apron mechanism 22. Write the advantages of automat over conventional lathes (i) Mass production is identical parts (ii) High accuracy is maintained (iii) Time of production is minimized (iv) The bar stock is feed automatically

23. What is called carrier plate and lathe dog?

Carrier plate – Threaded hole mounted on lathe spindle for transfer motion

Lathe dog – Transfer motion from driving plate to workpiece between centers

24. Differentiate semi-automatic and automatic lathe.

Semi-automatic – Loading and unloading can be done manually

Automatic lathe - Capable of producing identical process at a time with auto set up

ME8451 Manufacturing Technology – II Question Bank Unit 3 – , and Gear Cutting Machines

1. Mention the differences between shaper and .

Sl No Shaper Planar Tool reciprocates and the Tool is stationary and work 1 work is stationary reciprocates It gives more accuracy as the tool Less accuracy due to 2 is rigidly supported during overhanging of ram cutting.

2. What are the differences between drilling and reaming? Drilling is the operation of producing cylindrical hole in a work piece. It is done by rotating the cutting edge of a cutter known as . The work is rotated at high speed. Reaming is the operation of finishing and sizing hole which is already drilled while the work is revolved at a very slow speed.

3. Briefly describe the importance of quill mechanism. If the taper shank of drill is smaller than the taper in the spindle hole, a sleeve is used. The sleeve with drill is fitted in the hole of the spindle. The sleeve has outside taper surface. This fits into the tapered hole of the spindle.

4. List the types of sawing machines. Types of sawing machines are (1) Reciprocating saw (2) Circular saw (3) Band saw

5. Define the cutting speed, feed and machining time for drilling. Cutting Speed: It is the peripheral speed of a point on the surface of the drill in contact with the Work piece. It is usually expressed in m/min. Feed: It is the distance of a drill moved into the work at each revolution of the spindle. It is expressed in mm/rev. Machining time: The time taken to complete the machining process without considering the idle time of machines is called machining time.

6. What is ? It is a process of machining a surface with a special multipoint cutting tool called “BROACH” which has successively higher cutting edges in a fixed path.

7. What is the difference between up milling and down milling? Sl Operation Up Milling Down Milling No 1 Direction of Cutter rotates against Cutter rotates in the travel the same direction of direction of travel of travel of work piece work piece 2 Cutting Force Increases from zero to Decreases from max to max zero per tooth. per tooth

8. List four applications of broaching machines. (i) Straight and helical slots (ii) External surfaces of various shape (iii) External and internal toothed gears (iv) Holes of cross sectional shape

9. How do you classify milling cutters? They are classified based on following factors (i) According to the shape of the teeth. (ii) According to the type of operation (iii) According to the way of mounting on the machine

10. What do you know about straight fluted drill and fluted drill? The with helical flutes provides smooth shear cutting action and provides better surface finish .The pitch of the flutes is made uneven to reduce vibration.

11. Write the differences between drilling and tapping. Drilling is the operation of producing cylindrical hole in a work piece. It is done by rotating the cutting edge of a cutter known as drill. The work is rotated at high speed. Tapping is the process used for making internal threads in a machine component by a tool called “TAP”

12. Differentiate conventional and climb milling? Conventional milling Climb milling Work is feed against the rotating cutter Work moves parallel to the cutter rotation Thickness of the chip is minimum in the Thickness of the chip is maximum in the initial stages and increases maximum at initial stages and minimum at the end of the end of the cut the cut Cutter lifts the work, so requires more Cutter holds the work. Requires less claiming force claiming force Surface finish is not good, Good surface finish

13. State the differences between a vertical shaper and slotters.

Sl Vertical Shaper Slotter No. Vertical generally fitted Rotary table along with tools 1 with rotary table to will move machine curved surfaces Slides will move to perform 2 Slides are fitted slotting.

14. What is a shell mill? A shell mill is a large type of face or , rather than having an integral shank. Typically there is a hollow or recess in the centre of the shell mill for mounting hardware on to a separate arbor.

15. Mention the operations performed by a planner. a. Planning horizontal surface b. Planning of an angle c. Planning vertical surface d. Planning curved surface

16. Why is sawing a commonly used process. a. Easy handling of machines and spindle construction b. Fast operation and cost of machinery is less

17. What is straddle milling? It is just like side milling with difference that cutting (milling operation) takes place simultaneously on both the sides of work piece as shown in the figure.

18. What do you mean by differential ? Differential indexing is similar to compound indexing except that the index plate is turned during the indexing operation by gears connected to the dividing head spindle. Because the index plate movement is caused by the spindle movement, only one indexing procedure is required. The gear train between the dividing head spindle and the index plate provides the correct ratio of movement between the spindle and the index plate.

19. Why is milling a versatile machining process? Milling machines are very versatile. It is usually used to machine flat surfaces, but can also produce irregular surfaces. It can also be used to drill, bore, cut gears, and produce slots.

20. What do you understand by Gang milling? Gang milling is the process of producing many surfaces of a job simultaneously by feeding the table against a number of required cutters. In gang milling, being employed, where feasible, for quick production of complex contours comprising a number of parallel flat or curved surfaces a proper combination of several cutters are mounted tightly on the same horizontal milling arbour.

21. What is gear finishing? Why it is done? Surface of gear teeth with accurate and of good quality cannot be produced by any of the generating processes. Dimensional inaccuracies and rough surface generated so become the source of lot of noise, excessive wear and backlash generated between the pair of gear in mesh, so the result of the loss of power to be transmitted and incorrect velocity ratios. Therefore, these gears cannot transmit power efficiently. Hence these problems can be overcome by finishing operations.

22. Name any four work holding driven in shaper. (i) Shaper vice (ii) Angle plate (iii) V-Block (iv) Clamps

23. List out the various milling operations. (i) Plain or Slab Milling (ii) Face Milling (iii) Angular Milling (iv) Straddle Milling

24. List the applications of gear . Gear hobbing is used for generating spur gear, helical gear and worm gear

25. Define lapping The lapping process only corrects minute deviations from the desired gear tooth profiles. The gear to be finished after machining and heat treatment and even after grinding is run in mesh with a gear shaped lapping tool or another mating gear of cast iron. An abrasive lapping compound is used in between them. The gear tooth contact substantially improves by such lapping.

26. Define gear shaving. The teeth of straight or helical toothed external spur gears and worm wheels of moderate size and made of soft materials like aluminium alloy, brass, bronze, cast iron etc. and unhardened steels are mostly finished by shaving process.

27. Why reaming operation is performed? Reaming is a machining process that uses a multi edges fluted cutting tool to smoothen, enlarge or accurately sized an existing hole. It is performed using drilling machine

27. Define cutting ratio of the shaper The ratio between the cutting stroke time and the return stroke time is called as cutting ratio.

ME8451 Manufacturing Technology – II Question Bank Unit 4 – Abrasive Process and Broaching

1. What are the specifications of grinding wheel? (a) Type of bond (b) Grit or grain size (c) Grade (d) Structure Abrasive (e) Manufacturer’s Code

2. What is honing? An abrading process of finishing previously machined surfaces is called honing.

3. Narrate the working principle of abrasive jet machining. In this type the electrolyte used is replaced by abrasive jet. But grinding process is as similar that of electrochemical grinding.

4. What is gear hobbing? The process of generating a gear by means of rotating a cutter called HOB is known as HOBBING.

5. Define hardness of the grinding wheel. Grade or hardness indicates the strength with which the bonding material holds the abrasive grains in the grinding wheel.

6. Define lapping. Lapping is a surface finishing process used for producing geometrically accurate flat, cylindrical and spherical surfaces.

7. What is meant by “grade” and “structure” of a grinding wheel? Grade or hardness indicates the strength with which the bonding material holds the abrasive grains in the grinding wheel. Structure denotes the spacing between the abrasive grains or in other words the density of the wheel.

8. What are all the parameters that would affect the MRR in abrasive jet machining? The metal removal rate is affected by the following factors Grinding wheel speed Type of abrasive used Capacity of pump Capacity of filter

9. Mention four important factors that influence the selection of grinding wheel. (1) Constant factors (a) Physical properties of material to be ground (b) Amount and rate of stock to be removed (c) Area of contact (d) Type of (2) Variable factors (a) Work speed (b) Wheel speed (c) Condition of grinding wheel

10. What is roller burnishing process? It is a method of cold working metal surfaces in which hardened sphere or cylindrical roller is pressed against the work to be processed

11. What is the need of truing and dressing operations in a grinding wheel? To break away the glazed surface so that the new sharp abrasive particles are again present to work for efficient cutting To trim the cutting surface of the wheel to run true with the axis.

12. List the advantages of honing? Simple process which can be done on any general purpose machines such as lathes and drilling machines. This process can be applied for both internal cylindrical and flat surfaces. Honing enables the maximum stock removing capacity out of entire surface finishing operation.

13. State the abrasives used in manufacture of grinding wheels. (1) Natural abrasives (a) Sandstone or solid quartz (b) Emery (c) Corundum (d) Diamond (2) Artificial abrasives (a) Aluminium oxide (b) Silicon carbide (c) Artificial diamond (d) Boron carbide (e) Cubic Boron Carbide

14. What are the types of surfaces that can be produced using plain cylindrical grinders? Plain cylindrical parts, Cylinders, Tapers, Shoulders, Fliers etc.,.

15. What do you mean by loading of grinding wheels? During operation, the chips formed get entrapped in the inner granular space of abrasive particles. This is called loading

16. How does wheel dressing differ from wheel truing? Truing is defined as the process of shaping the grinding wheel while it is mounted on the grinding spindle in order to remove out-of- roundness and to impart the desired profile to the surface of the wheel. Dressing which is sometimes performed after truing, is the process of conditioning the surface of the wheel to expose fresh abrasive particles.

17. How does loading differ from glazing in grinding process? Loading: During the operation the chips are formed get entrapped in the inner granular space of abrasive particles Glazing: Surface of the wheel becomes smooth and gets a glass like appearance

18. What are the principal types of broaching machines? (i) Horizontal broaching machine (ii) Vertical Broaching machine (iii) Surface broaching machine (iv) Continuous broaching machine

19. What do you mean by duplex broach? Duplex broaching is a machining process that uses a toothed tool, called a duplex broach to remove material.

20. Define grinding ratio Wheel life in grinding is expressed as a grinding ratio, G, defined as the volume of material removed per unit volume of grinding wheel wear. G-ratio is an important parameter because it is directly related to wheel cost for most operations.

21. Why broaching process is long and laborious? Broaching is a machining operation that involves the use of a multiple, tooth cutting tool moved linearly relative to the work piece in the direction of the tool axis. So broaching process is long since all the machining parameters are built into the broach, skill is required from the operator.

ME8451 Manufacturing Technology – II Question Bank Unit 5 – CNC Machining

1. Define NC. Automatically controlling a machine tool based on a set of pre- programmed machining and movement instructions is known as numerical control, or NC.

2. Name the major elements of NC machines.  Tape reader  Mini computer  Servos and interface logic  Motion feedback

3. What are the classifications of NC machines?  Point to point NC system  Straight cut NC system  Contouring NC system

4. What is the role of computer for NC machine tool? Computer numerical control is an NC system that utilizes stored program to perform basic numerical control functions .Mini or microcomputer based controller unit is used.

5. Define DNC. Distributive numerical control or Direct Numeric Control (DNC) is a technology that allows a single computer to be networked with one or more machines that use computer numerical control (CNC) through connection and in real time. Using DNC, an operator can quickly load CNC programs into multiple machines. It is also possible to remove programs and replace them with updated or modified programs.

6. What is the difference between incremental and absolute system. In an incremental system the movements in each Part program block are expressed as the displacements along each coordinate axes with reference to the final position achieved at the end of executing the previous program block.

An absolute NC system is one in which all position coordinates are referred to one fixed origin called the zero point

7. What are G-Codes and M-Codes? G- Codes are preparatory function codes which prepare the machine or tool for different modes of movement like positioning, contouring, thread cutting etc.

M-codes are miscellaneous function codes which denote the auxiliary or switching information such as coolant on / off, spindle speed etc.

8. Define Part programming Part program is a set of instructions often referred to as blocks, each of which refers to a segment of the machining operation performed by the machine tool. Each block may contain several code words in sequence. These provide: (i) Coordinate values (X, Y, Z, etc.) (ii) Machining parameters such as, feed rate, spindle speed, tool number, tool offset compensation parameters etc. (iii) Codes for initiating machine tool functions (iv) Program execution control codes 9. List the differences between NC and CNC.

NC Machine CNC Machine NC stands for Numerical Control CNC stands for Computer Numerical Control. It is defined as the machine which is It is defined as the machine which is controlled by the set of instructions used to control the motions of the in the form of numbers, letters and work piece and tool with the help of symbols. The set of instructions is prepared program in computer. The called as program. program is written in alphanumeric data. In NC machine the programs are fed In CNC machine the programs are into the punch cards. fed directly into the computer by a small key board similar to our traditional keyboard. Modification in the program is Modification in the program is very difficult. easy. The programs in the NC machine In CNC machines, the programs can cannot be stored. be stored in the computer and can be used again and again. The accuracy is less as compared with It has high accuracy. the CNC. High skilled operator is required. Less skilled operator is required. Cost of the machine is less. Cost of the CNC machine is high. Maintenance cost is less Maintenance cost is high.

10. What are feed drives? Feed drives are used to drive the axis as per the programme fed in the CNC machine.

11. What is meant by APT language? It is the abbreviation of automatically programmed tools. APT program is used to command the cutting tool through its sequence of machining process. APT is also used to calculate the cutter positions. APT is a three dimensional system controlling up to five axes including rotational coordinates.

12. Write down the types of statements in APT language. (i) Geometric statements (ii) Motion statements (iii) Post processor statements (iv) Special control or auxillary statements

13. Compare a closed loop NC system with open loop system.

Open loop Closed loop The term open-loop means that there is A closed loop system is also no feedback, and in open loop systems referred as a feedback control the motion controller produces outputs system. These systems record depending only on its set points, without the output instead of input and feedback information about the effect modify it according to the need. that the output produces on the motion It generates preferred axes. condition of the output as compared to the original one. It doesn’t encounter any external or internal disturbances. The primary drawback of open-loop The control law takes the error system is that there is no feedback as the input and drives the system to check whether the actuator, in this case the servo commanded position and velocity has motor and its drive system, to been achieved. achieve motion variables that are close to the set points.

14. What is a preparatory function? How is it important in CNC programming? Preparatory commands which prepare the machine or tool for different modes of movement like positioning contouring, thread cutting and also proceed the dimension word .They are grouped .Group cannot affect each other. Only one function from the same group can be at the same time.

15. Write the advantages of a CNC Machine (i) Higher flexibility (ii) Increased productivity (iii) Improved quality (iv) Reduced scrap rate (v) Reliable and Safe operation (vi) Several machines are fused into one.

16. State the limitations of CNC machine tools. (i) CNC machines are more expensive than manually operated machines, although costs are slowly coming down (ii) The CNC machine operator only needs basic training and skills, enough to supervise several machines. (iii) Less workers are required to operate CNC machines compared to manually operated machines

17. State the limitations of NC machine tools. (i) Relatively higher cost compared to manual versions (ii) More complicated maintenance due to the complex nature of the technologies (iii) Need for skilled part programmers. (iv) It offers less flexibility and computational capability. (v) It requires more time for the execution of the job.

18. What are linear bearings? A linear motion bearing or linear slide is a bearing designed to provide free motion in one dimension. Linear motion bearings are widely used to guide, support , locate and accurately move machinery components and products in a wide range of application.

19. State the functions of the following G and M codes? G01 G04 M04 M30 G01 - Linear move G04 – Dwell M04 - spindle on CCW M30 - end of tape (rewind)

20. Compare Bulk and surface micro machining Process. Bulk micromachining, the oldest of the micromachining technologies, is accomplished by removing material from a substrate to create holes, cavities, channels, or other desired shapes Surface micromachining etches away layers deposited on top of the silicon substrate. The process starts with a silicon wafer, upon which structural and sacrificial layers are deposited. Surface Micromachining is the process of forming movable structures by placing the structures on initially rigid platforms, then removing the platforms, usually by etching the material away.

21. Define micromachining? Micro machining is defined as the ability to produce features with the dimensions from 1 µm to 999 µm or when the volume of the material removed is at the micro level. Classification of micromachining methods as shown in figure.

22. Mention the type of ball .

23. Differentiate Automation and Mechanization. Mechanization is normally defined as the replacement of a human task with a machine. Automatic transplants are an example of mechanization. Automation involves the entire process, including bringing material to and from the mechanized equipment. It normally involves integrating several operations and ensuring that the different pieces of equipment talk to one another to ensure smooth operation. Many times, true automation requires re- evaluating and changing current processes rather than simply mechanizing them.

24. What is adaptive control? Adaptive control is the capability of the system to modify its own operation to achieve the best possible mode of operation. Flow chart as shown in figure.